Before I discuss this question, I'll give you my original setup.
A 8 _ X _ _
M _ 4 _ 7 X M T W R F
This question says: The crew cleaned 6 on a morning The crew cleaned 2 before 7
6 has to be after 4. What is the only morning available after 4? Wednesday. 2 has to be in the afternoon. What is the only afternoon available before 7? Tuesday.
A 8 2 X _ _
M 1/3 4 6 7 X M T W R F
We have placed most of our streets. Who remains? 1, 3, and 5. We know that 5 must be in the afternoon, which is why either 1 or 3 must be on Monday morning. This is why the answer is C. We don't know exactly where 1, 3, and 5 must go.
